Living Sanibel

September 20, 2013

Often swimming in schools with threadfin herring, the scaled sardine, or whitebait as it is commonly referred to, is one of the most popular baitfish in Southwest Florida. In parts of Mexico, the Caribbean and the northern coast of South America the scaled sardine is harvested for human consumption where it is primarily canned. It is not currently used as a human food source in the United States. Scaled sardines range as far north as the coast of New Jersey to southern Brazil in waters from fifteen to one-hundred and twenty feet deep.

Scaled sardines feed on zooplankton but will also take shrimp, squid and small pieces of cut bait. This minnow is a very important link in the estuarine and coastal food webs. They are preyed upon by everything, from sharks to king mackerel. Bottlenose dolphins feed heavily on mature schools of sardines just as the herons, egrets, gulls and pelicans feed on the smaller, immature schools.

All minnows are susceptible to water quality degradation. When harmful algae blooms occur (HABS), scaled sardines and threadfin herring are one of the first fishes to be impacted. If they are unable to flee the immediate area, entire schools can be destroyed in hypoxic events (often called dead zones). These dead zones occur when a rapid increase in nutrients (primarily nitrogen and phosphorus) create a condition called eutrophication, leading to harmful algae blooms. When the algae blooms created by the over-nitrification (also commonly called cultural eutrophication) of the estuary begins to decompose, it uses all of the available oxygen in the process, which effectively suffocates all the living organism within the immediate region (note: because these effects are man made, they are referred to as "cultural eutrophication"). Once these fish populations collapse, the birds, marine mammals and fish population that rely on this food source quickly follow suit.

Article Photos

Scaled sardine. Diane Peebles.

While lawn fertilizers may make your yard look attractive, the use of these chemical nutrients come at a steep price. That price tag is the loss of a healthy estuary further downstream. As a species we have to learn that we cannot have it both ways. For every action there is a reaction and when it comes to landscaping, well-manicured lawns are an environmental tragedy.

-This article is an excerpt from Living Sanibel-A Nature Guide to Sanibel & Captiva Islands by Charles Sobczak. The book is available at all the Island bookstores, Baileys, Jerry's and your favorite online sites.